[DOC] Release notes for Pyroscope 1.3

[knylander-grafana]

Create release notes for the next release.

Tasks:

• Create a summary of the new features and major improvements
• Verify docs are available for ther updated features and link to those docs from the release notes
• Update the "Upgrade to Pyroscope" page with any breaking changes or caveats for the next release

[knylander-grafana]

Major new features:

• Downsampling and compactor performance improvements are new

Draft content from Ryan:

New Features

• Enhanced symbol compaction process: Improved performance and storage efficiency with the new symbol compaction process (feat: Improve symbols compaction #2864).
• Introduced function selector in pprof query: More precise profiling with the addition of a function selector (feat: add function selector to pprof query #2878).
• Support for time-based downsampling during compaction: Optimized data processing with time-based strategies (Time based downsampling during compaction #2880).
• Added tracing integrations to compaction: Better observability in the compaction process (feat: Add tracing integrations to compaction #2876).
• Added language mapping for Grafana agent in Java: Expanded profiling capabilities (Add grafana-agent.java language mapping #2866).

Improvements and Updates

• Updated Alpine and Golang versions: Enhanced security and performance with the latest versions of Alpine (3.18.5) and Golang (1.21.5) (Update alpine version to 3.18.5 #2901, Update golang version to 1.21.5 #2902).
• Injected JFR labels into pprof: Enriched profiling data for better insights (fix: inject JFR labels into pprof #2868).
• Streamlined Makefile and go.mod: Better build process with updated Makefile and tidied go.mod (chore: Makefile cleanup go.mod tidying #2900).
• Updated agent configuration in Helm: More flexible deployments in Kubernetes environments (Helm: update agent configmap creation condition #2879).
• Refactored ebpf installation documentation: Improved clarity and usability in ebpf documentation (docs: Refactor ebpf installation #2849).
• Upgraded connect-go, protobuf, and buf: Improved system interoperability (Refactor: Upgrade connect-go, protobuf and buf #2909).
• Enhanced compaction shutdown process: Improved system stability during shutdowns (feat: Improve compaction shutdown #2903).
• Implemented profilecli compact command: Efficient data management with the new command (feat: profilecli compact command #2869).

Fixes

• Fixed panic in compaction benchmark: Addressed issues causing system instability (bugfix: Fixes panic in compaction benchmark #2918).
• Resolved block cleanup process issues: Ensured system integrity and stability (fix: Skip non-tenant directories during block cleanup #2916).
• Fixed pprof profile builder panics: Enhanced system stability (fix: pprof profile builder panics #2917).
• Corrected profile types call handling: Better data management without bucket store (Handle profile types call properly without bucket store #2910).
• Removed delta reserved labels from storage: Optimized the storage system (refactor: Removes the delta reserved labels from storage. #2920).
• Increased parquet read buffer size: Improved data processing efficiency (Increase parquet read buffer size #2924).

Documentation Improvements

• Enhanced memory overhead documentation: Deeper insights into system performance ([DOC] Add memory overhead doc #2895).
• Updated NodeJS documentation: Fixed Markdown link issues for better clarity (fix NodeJS Docs Markdown link #2890).
• Expanded java.md documentation: Comprehensive Java profiling guidance (Update java.md #2904).
• Removed dependency on Grafana agent: Streamlined Pyroscope architecture (remove dependency on grafana agent #2913).
• Updated various sections: Intro, analyze, sampling, and SDK pages now offer clearer and more detailed information ([DOC] Updated intro and analyze sections #2855, docs: update go-pull.md #2844, docs: Add sampling documentation #2854, docs: language SDK page updates #2851, doc: Add sampling diagram #2861).
• Launched a 1-minute YouTube short on ebpf: Providing a quick and informative overview of ebpf (add 1 min youtube short video on ebpf #2893).